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Yuan Xie, Yunxiao Sun, Diya Yang, Yiquan Yang, huaizhou wang, Guozhong Wang, Ningli Wang; Impact of acute hypobaric hypoxia on anterior chamber geometry. Invest. Ophthalmol. Vis. Sci. 2020;61(7):1863.
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© ARVO (1962-2015); The Authors (2016-present)
To quantify the impact of exposure to hypobaric hypoxia( equivalent to 4000m above sea level) on the geometry of the anterior chamber in healthy lowlanders.
Twenty-five healthy young individuals were passively exposure to simulated 4000m above sea level within 15 minutes. Horizontal images from 2-dimensional angle analysis scans appling a CASIA SS-1000 (Tomey, Nagoya, Japan) were measured and evaluated by masked readers. The parameters assessed included :angle opening distance at 500 m from the scleral spur (AOD500), trabecular-iris space area at 500 m from the scleral spur(TISA500), anterior chamber depth (ACD), anterior chamber width (ACW) and pupil diameter (PD). Intraocular pressure (IOP) was measured by Icare tonometer. Blood pressure (BP) was assessed by by one observer with an electronic sphyg- momanometer (HEM-7133; Omron Corporation, Kyoto, Japan), and heart rate (HR) ,pulse oxygen were recorded by a finger pulse oximeter (PC-60NW; Health force, Shanghai, China) before and after acute exposure to hypobaric hypoxia.
Compared with sea level, The average IOP (16.38±3.59 versus 14.87±2.08 mmHg,p=0.007) and pupil size （5.346±0.77 versus 4.782±0.888 mm,p<0.001）significantly decreased, while AOD500 (0.887 ±0.422 versus 1.059 ±0.478 mm, p=0.022), ACW（2.015±3.705 versus 2.482 ±3.988 mm,p=0.045）, ACA（48.949±17.111 versus 51.808 ±14.444 degree,p=0.043） significantly increased. The ACD (3.086 ± 0.677 versus 3.184± 0.317 mm; p = 0.906) and TISA500 (0.386± 0.249 versus 0.475 ± 0.272 mm2; p = 0.054) showed no significant change after exposure to high altitude. The blood oxygen,heart rate and BP decreased during exposure to high altitude but resolved after immediately returned to sea level. Anterior chamber parameters were not associated with IOP and pupil size.
There was an decrease in IOP and pupil size, while an increase in anterior chamber angle after exposure to hypobaric hypoxia. These changes in anterior chamber structure were only associated with hypoxia, but not with the post-exposure change in PD or IOP.
This is a 2020 ARVO Annual Meeting abstract.
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